A record 9.16 million barrels per day of motor gasoline was consumed in 2005. The average price of a gallon of gasoline in the United States is approaching four dollars as of June 2008.
Traffic data presented in the 2005 annual Urban Mobility Report by the Texas Transportation Institute at Texas A&M University for peak commuting hours in 85 metropolitan areas in 2005, when the average price of gasoline was $1.45 per gal, showed an annual total of 3.7 billion hours of delay, 2.3 billion gallons of extra fuel used and a total cost of $63.1 billion per year. About 70% of this cost is from fuel costs, so at $4 per gal, this total cost is now at least $140 billion, an amount which, if it were the revenues of a company, would put it among the ten largest companies in the United States.
In general, traffic congestion is worse in larger urban areas than in smaller ones. Traffic congestion levels have increased in every area since 1982. Congestion extends to more times of the day and more roads, affects more travel, and creates more extra travel time than in the past. Congestion levels have risen in all urban size categories, indicating that even smaller areas are not able to keep pace with rising demand. The need for attention to transportation projects is illustrated in these trends. However, major transportation projects require a significant planning and development time—10 years is not an unrealistic timeframe to go from an idea to a completed project or to an accepted program. At recent growth rates, the average congestion for medium-sized urban areas in 2013 will have the congestion problems of large areas in 2003.
Congestion travel time penalties are related to size of the area. The delay per traveler increases with population, but there is a significant amount of variation within groups. Areas that have seen high rates of growth in recent years are more likely to be near the top of their population group because demand has increased much faster than the corresponding increase in roadway capacity, public transportation services, traffic control infrastructure, and land use patterns.
The Urban Mobility Report shows that:                Areas with populations over 3 million (Very Large) can expect a minimum annual delay per traveler of 38 hours;        Areas with populations over 1 million (Large and Very Large) can expect a delay per traveler of at least 10 hours with a more likely value of around 37 hours;        Areas with populations over 0.5 million (all except Small) should expect at least 7 hours with typical values being closer to 20 to 30 hours; and        Areas with populations less than 0.5 million (Small) should expect a delay per traveler of up to 25 hours.        
Traffic congestion affects a broader segment of the transportation system each year. Congestion has spread to more cities, more of the road system, more trips within a given city, more time during the day, and more days of the week in some locations. Comparing 1982 to 2005, the Urban Mobility Report finds that:                28 urban areas had a Travel Time Index above 1.30 in 2003 compared with only one such area in 1982;        67% of the peak period travel was congested in 2003 compared to 32% in 1982;        59% of the major road system was congested in 2003 compared to 34% in 1982;        The number of hours of the day when congestion might be encountered grew from about 4.5 hours to about 7.1 hours; and        Most of the trend information indicates that the 2003 average values for each population group are near the 1990 value for the next highest population group. This is also the case for the 1990 and 1982 comparison. This suggests that each group will attain congestion levels of the next higher group approximately each decade if trends are not reversed.        
The Urban Mobility Report also gives the cost per traveler for each population group as reproduced in Table 1.
TABLE 1Congestion Effects on the Average Traveler in 2003AverageAverage cost perAverage delay perfuel used perPopulation grouptravelertraveler (hrs)traveler (gal)Very large$1,038  6136Large$6203723Medium$4182515Small$222138Average for 85$7944728areas
How much more transportation capacity would be needed to alleviate congestion? This is a difficult question to answer. Most urban areas implement a wide variety of projects and programs to deal with traffic congestion. Each of these projects or programs can add to the overall mobility level for the area. Thus, isolating the effects of roadway construction is difficult, because these other programs and projects make a contribution at the same time. In any case, the relevancy of the analysis is questionable. Many areas focus on managing the growth of congestion, particularly in rapid-growth areas. The analysis presented in the Urban Mobility Report is not intended to suggest that road construction is the best or only method to address congestion. It also concludes that it would be almost impossible to attempt to maintain a constant congestion level with road construction only. Over the past two decades, only about 50% of the needed mileage was actually added. This means that it would require at least twice the level of current road expansion funding to attempt a road-construction-only strategy. An even larger problem would be to find suitable roads that can be widened, or areas where roads can be added, year after year. Most urban areas are pursuing a range of congestion management strategies, with road widening or construction being only one.
How many new carpools or bus riders would be needed if that were the only solution? The Urban Mobility Report shows the increase in occupancy level in order to maintain existing congestion levels and concludes that the aforementioned 85 urban areas added more than 52 million additional miles of daily person travel in 2003. To accomplish a goal of maintaining a constant congestion level in these areas by only adding transit riders and carpoolers, there would have to be a substantial growth in these modes. The growth would be equivalent to an additional 3-4% of all vehicles becoming carpools, or expanding transit systems by more than one-third of the current ridership each year. It may be very difficult to convince this many people to begin ridesharing or using public transit. There has been some success with this solution, and in conjunction with other techniques, there may be some opportunity to slow the mobility decline.
The above summary of data and conclusions from the Urban Mobility Report clearly defines the urban mobility problem, its spread, cost, and possible solutions which have historically been considered. Solutions implemented and suggested to date are generally location specific, require heavy capital investment, involve lengthy temporary traffic diversion affecting traffic at all hours, cause additional temporary congestion during commuting hours, and are expensive. These solutions include building high-occupancy vehicle (HOV) lanes, new roads, or new lanes on existing roads, or alternatively building parallel rail lines, adding commuter buses, etc. Developed countries like the United States, could actually afford many of these suggested conventional solutions, although they would still suffer ongoing and worsened congestion until these high-capital-investment projects are completed. They would still be incurring financial loss of tens of billions of dollars per year until implementation is complete (assuming constant congestion, economic health, and stable fuel prices; we have already observed that congestion has gotten steadily worse every year since 1982).
In addition, the roadway improvement solutions mentioned above are not dynamic in the sense that new capacity would be available for both non-commute hours and commute hours. In effect, excess average capacity must be built to accommodate peak demand during commute hours.
Various proposals have been made to address these problems. Stankiewicz (U.S. Pat. No. 3,847,496) discloses an integrated highway, parking, and mass transit system. Avery (U.S. Pat. No. 3,541,962) teaches an urban aerial car transit system with overhead rails. Clayton (U.S. Pat. No. 5,921,701) teaches the building of a center-turning overpass. These proposals generally require very expensive infrastructure changes to the current road system; some of them can be implemented only in newly developing areas. In some urban areas both sides of the freeway are choked during peak commuting hours, and there is no space to expand the roadway or even to provide bypass routes during construction.
Hassett (U.S. Pat. No. 5,289,183) discloses automatic traffic monitoring. He proposes a variety of sensor means for detecting traffic conditions and therefore congestion, but does not provide means to relieve congestion.
Hameleers (U.S. Pat. No. 6,694,247) discloses flexible traffic management with real-time changes depending on real-time traffic information. The dynamic changes suggested include changes to speed limit, traffic signs, parking lanes, use of one or two lanes, etc.
Yang et al. (U.S. Pat. No. 7,155,376) discloses a traffic simulation system and methods for traffic analysis and traffic data management with geographic information. No methods of relieving congestion are provided.
TIME Magazine, Sep. 12, 1988, has a cover story about grid-lock. The article describes possible solution to the highway problem; however it indicates that automobile use is a valued personal liberty for U.S. residents and that they are not likely to abandon their automobile for use of mass transit.
Some commuters use cycles, motorcycles, and scooters to travel through congested traffic areas more easily than conventional vehicles. A conventional two-wheeled motorcycle or scooter seats one or two people on a narrow vehicle generally not more than 3 ft wide. They can often be observed to travel between lanes of stalled or slow traffic, although this is a dangerous practice. Two-wheeled vehicles are inherently unstable at very low speed and when stopped and provide little protection for the riders during minor accidents and bad weather.
Present enclosed-body vehicles, known or available in the U.S. market usually range from 66-78 inches in width. These vehicles generally have at least four wheels, with one or more rows of seats and each row with at least two seats. This minimum width is dictated in part for safety against rollover. Only one such vehicle can safely travel in the width of a normal lane—indeed lanes are designed to accommodate the width of these vehicles with a suitable safety margin from adjacent lanes.
Vehicles with narrow widths are known to achieve higher transportation efficiency with one or more people seating in tandem positions (one behind the other). Such narrow vehicles are susceptible to rollover unless specifically stabilized. Boughers (U.S. Pat. No. 4,003,443), Trautwein (U.S. Pat. No. 4,020,914), Parham (U.S. Pat. No. 4,064,957), and Winchell (U.S. Pat. No. 4,065,144) disclose such stabilizing devices using spring arrangements acting between the wheel suspension and the remainder of the vehicle. The vehicle always tends to return to its upright position. During normal operation, such vehicles could interfere with other vehicles around them which do not tilt in a similar manner.
Jephcott (U.S. Pat. No. 4,484,648) and Tidwell (U.S. Pat. No. 4,283,074) disclose vehicles arranged to bank, tilt, or roll toward the inside of a turn. The amount of roll required is dependent upon the speed and radius of the turn. This requires real-time processing of data, and the vehicle must be under precise electronic and hydraulic control. During normal operation, such vehicles could dangerously interfere with other vehicles around them, which do not tilt the same way. Also, the systems cause uneven tire wear and require careful maintenance, as failure of such systems can cause the vehicle to lose control. Manufacturing and maintenance costs are high.
McCrary (U.S. Pat. No. 6,276,542) discloses dual mode vehicles. These vehicles incorporate cruise control and automatic collision avoidance features for reduced commuting stress during normal road conditions and provide a manual mode when needed. Unfortunately, they do not reduce congestion.
Pivar (U.S. Pat. No. 4,313,517) discloses a three-wheeled vehicle with a low center of gravity (18 inches from ground with internal combustion engine and two 200-lb occupants) with side-by-side seating for two people that can make a 90°-turn with a radius of 47 ft at a speed of 13 mph. It has 30-50-mile range with battery-powered motor and top speed of 20 mph, so that it can never be a viable commuter vehicle for arterial streets and freeways, and it is not a narrow vehicle.
Woodbury (U.S. Pat. No. 6,328,121) discloses an ultra-narrow enclosed vehicle with a width of about 3 ft, stabilized with the aid of a ballast weight of 950 lbs, giving a curb weight of 1600 lbs. This ballast is the equivalent of about five extra passengers, and results in the need for a correspondingly larger engine or motor and higher fuel consumption.
Conventional means for reducing congestion include increasing the number of lanes, creating “high occupancy vehicle” (HOV) lanes, adding parallel rail transit, ride sharing, and public or private bus transport. All of these solutions suffer from one or many of the following drawbacks, including high capital investment, loss of usable lanes (e.g., underutilized HOV lanes), difficult to adapt to changing traffic demands, high operating costs (e.g., bus and rail systems that are not operating at full capacity, bus fuel and travel time inefficiencies and inflexibility when used in congested traffic). These solutions tend to be rigid and non-adaptable to the cyclic and dynamic conditions that are present on real roadways, and do not provide flexibility for commuters.